1. Technical Field
The present invention relates to a virtual image display apparatus and a projector that present a video formed by a video display apparatus to an observer and, more particularly, to a virtual image display apparatus suitable for a head mounted display mounted on the head of the observer.
2. Related Art
Various virtual image display apparatuses are proposed as a virtual image display apparatus such as a head mounted display (hereinafter also referred to as HMD) mounted on the head of an observer (see, for example, JP-A-2012-163640 (Patent Literature 1)).
The virtual image display apparatus such as the HMD is desired to attain an increase in an angle of view without deteriorating image quality while being reduced in size and weight.
When an observer views a video on a television or the like, if the observer views the video for a long time in a straight forward state, the observer observes the video in a wide-open state of the eyes because of the structure of the human eyes. As a result, a large burden is imposed on the eyelids and the like of the observer. Therefore, it is important for the observer to adjust a posture to observe the video in a state in which the direction of the eyes (the visual line) of the observer is naturally directed to the downward side with respect to the television or the like by setting the visual line to a visual line angle in a relaxed state with the eyes closed called dark focus. The burden on the eyes during the observation also occurs in observation of a video with a virtual image display apparatus such as an HMD. If the observer looks straight forward and the burden is imposed on the eyes for a long time, the observer feels stress due to fatigue in the eyes.
However, in the observation on the virtual image display apparatus such as the HMD, the observer observes the video while wearing the apparatus, unlike the observation on the television or the like, it is difficult to change the posture of the observer according to the position of the video. Further, because of individual differences such as the sizes and a positional relation of the eyes, the ears, the nose and the like of the observer, a position where the video is seen changes. Even if the virtual image display apparatus is designed such that the visual line of the observer is directed to the downward side in a standard worn state, the observation of the video is not always performed as designed.